食品微生物对超高压处理的逆境响应

 超高压（High Hydrostatic Pressure,HHP）作为一种非热杀菌技术,在食品工业中有着很广泛的应用,与传统的热加工处理相比,在保持食品品质、杀菌、钝酶等方面都有其明显的优势。通过对国内外相关文献的分析,对HHP处理后处于亚致死状态食品微生物的细胞膜、遗传与结构物质、机体代谢等方面,以及大部分食品微生物在应对外界的多种刺激时而进行的普遍性调控机制的研究进行了总结,探讨了经过HHP处理后处于亚致死状态的食品微生物在逆境下存活的应激反应。     

表面增强拉曼光谱在食源性致病微生物检测中的应用研究

食源性致病微生物导致的食源性疾病已成为全球化的公共卫生问题。快速、有效地检测食源性致病微生物是实现食源性疾病预防与控制的关键环节，也是保障食品安全的技术关键。表面增强拉曼光谱(SERS)具有简单、快速、灵敏度高等优点，在食品安全、生物医学、环境监控等领域展现出良好的应用前景。介绍了近年来SERS在食源性致病微生物检测中的应用研究进展。对SERS技术概况、SERS增强理论及SERS增强基底进行了简要介绍，重点回顾了SERS在食源性致病微生物检测中的应用和发展现状。在食品安全分析方面，利用SERS与模式识别方法相结合对食品中常见食源性致病微生物能实现快速、有效鉴别，部分研究已应用于不同食品样品的分析，体现了SERS作为“指纹图谱”的分析优势；在医学诊断方面，SERS可对病理样品(如血液、尿液等)中食源性致病微生物进行快速检测，缩短了样本分析时间，使食源性疾病的快速诊断成为可能；随着微流控技术的发展，微流控平台结合SERS技术被称为“芯片实验室”应用于食源性致病微生物的检测，可提高分析的可控性，稳定性，特异性和灵敏度。通过对比分析，发现不同研究可采用不同分离方法、不同基底、不同目标捕获方式等实现了食源性致病微生物的检测，展示了不同方法间的差异性。已有研究表明了SERS在食源性致病微生物检测中应用可克服传统方法耗时等缺点，实现灵敏快速分析，为食品安全实时监控，食源性疾病即时诊断提供了有效的分析工具。同时，指出了SERS技术应用于食源性致病微生物分析依然面临很大挑战，(1)大多数研究并没有聚焦于实际样品，而标准培养液和实际样品的SERS检测存在较大差异，实际样品组分会对SERS响应产生干扰；(2)不同方法结果有较大差异，主要是由于纳米增强基底差异，吸附方式原理的差异，稳定性的差异等，因此需要更多深入研究进一步优化条件；(3)期望建立标准化的SERS方法替代传统技术，充分展示SERS作为新兴分析工具快速、灵敏、简捷的优势应用于食品安全，医学诊断等领域。将来，随着研究的深入及相关学科的发展，SERS作为极具潜力的快速分析工具，将在食品安全，生物医学等领域具有更广阔的应用前景。     

Uplift of microorganisms by electric fields above thunderstorms

Collections of microorganisms have been reported at altitudes above the tropopause where it is difficult to explain their presence. In fact, modern science can still not answer the question “How high can a microorganism be found?” This paper will describe our analysis of the ability of electric fields, related to the presence/formation of thunderstorms, to uplift either charged ice particles (which may contain microorganisms) or microorganisms, which inherently contain an electric charge, into the stratosphere. Here we show, via simulation, that strong electric fields found during thunderstorms could accelerate charged micron-scale particles rapidly up against the forces of drag and gravity. This uplift mechanism may therefore help explain the presence of microorganisms in the stratosphere at altitudes of 40 km and above.     

Prospects and application of ultrasound and magnetic fields in the fermentation of rare edible fungi

Ultrasound has the potential to be broadly applied in the field of agricultural food processing due to advantages such as environmental friendliness, low energy costs, no need for exogenous additives and ease of operation. High-frequency ultrasound is mainly used in medical diagnosis and in the food industry for the identification of ingredients and production line quality testing, while low-frequency ultrasounds is mainly used for extraction and separation, accelerating chemical reactions, auxiliary microbial fermentation and quality enhancement in food industry. Magnetic fields have many advantages of convenient use, such as non-toxic, nonpolluting and safe. High-intensity pulsed magnetic fields are widely used as a physical non-thermal sterilization technology in food processing, while weak magnetic fields are better at activating microorganisms and promoting their growth. Ultrasound and magnetic fields, due to their positive biological effects, have a wide range of applications in the food processing industry. This paper provides an overview of the research progress and applications of ultrasound and magnetic fields in food processing from the perspectives of their biological effects and mechanisms of action. Additionally, with the development and application of physical field technology, physical fields can now be used to provide significant technical advantages for assisting fermentation. Suitable physical fields can promote the growth of microbial cells, improve mycelial production and increase metabolic activity. Furthermore, the current status of research into the use of ultrasound and magnetic field technologies for assisting the fermentation of rare edible fungi, is discussed.     

The effect of the nanocarbon structures from laser pyrolysis on microorganisms evolution

The carbon nanoparticles existing in environment are an important factor on healthy either by their toxicity or by interaction with pathogen microorganisms, which can make them more resistant or induce a specific mutagenesis. To understand the role of the nanocarbon particles, a series of carbon nanopowders was synthesized by gas-phase laser pyrolysis from different hydrocarbon-based mixture and used to design cell culture media for Escherichia coli and Staphylococcus aureus. The microorganisms, grown in a given incubation time, were investigated by fluorescent markers (water soluble quantum dots). We report that structure and properties of the nanocarbons influence the behaviour of the aerobic microorganisms. We show that carbon nanopowders are oxygen supplier for microorganisms and, at the same time, due to the presence of polyaromatics or heterogeneous atoms existent in the reactive gas mixture, could have an inhibition/poisoning effect.     

Influence of high power ultrasound on natural microflora,pathogen and lactic acid bacteria in a raw meat emulsion

Raw meat emulsions may have natural, spoilage and pathogenic microorganisms due to the origin and characteristics of this food matrix. All of these microorganisms must be minimized during industrial processing to make food consumption safe and meet quality regulations. Therefore, in this research, the effect of probe ultrasound on the inactivation of three kinds of microorganisms in a raw meat emulsion is evaluated. The microorganisms are: natural microflora NAM, Listeria monocytogenes LIS, and Lactobacillus delbrueckii LAC. A high-intensity probe ultrasound system was used, during 1.0, 2.5, 5.0, 7.5 and 10 min, with pulsed waves of 0.0, 10, 20 and 30 seg, and 200, 250, 300, 350 and 400 W of power. The interrelation between time, wave pulse cycle, and power factors was assessed. The results showed a positive linear independence effect in the treatments without wave pulse for each microorganism, and a quadratic interaction with the time and the ultrasound power for the inactivation of the three kinds of microorganisms. Besides, the desirability function for the inactivation reached up to 60% of the microbial population with the probe ultrasound treatment, with 10 min, a 7.56 s wave pulse and 400 W of power. Thus, these results could be useful to decide the incorporation of mild and emerging technologies in a meat industry line process.     

Recent advances in the application of ultrasound in dairy products: Effect on functional,physical, chemical,microbiological and sensory properties

Alternative methods for improving traditional food processing have increased in the last decades. Additionally, the development of novel dairy products is gaining importance due to an increased consumer demand for palatable, healthy, and minimally processed products. Ultrasonic processing or sonication is a promising alternative technology in the food industry as it has potential to improve the technological and functional properties of milk and dairy products. This review presents a detailed summary of the latest research on the impact of high-intensity ultrasound techniques in dairy processing. It explores the ways in which ultrasound has been employed to enhance milk properties and processes of interest to the dairy industry, such as homogenization, emulsification, yogurt and fermented beverages production, and food safety. Special emphasis has been given to ultrasonic effects on milk components; fermentation and spoilage by microorganisms; and the technological, functional, and sensory properties of dairy foods. Several current and potential applications of ultrasound as a processing technique in milk applications are also discussed in this review.     

High Pressure Processing for Preservation,Modification and Transformation of Foods

Commercial, high pressure treated food products have been delivered to the Japanese, the US and the European market. Parallel to these development activities intensive research work has been carried out. Within the European Union three major research projects devoted to high pressure research have been completed and a sound knowledge base has been accumulated on inactivation kinetics of microorganisms and enzymes, on biopolymers (proteins, polysaccharides) as well as on real food systems ( e.g. juices, dairy product, meat, fish, fruits and vegetables). One of the obstacles in furthering high pressure development in Europe is the current Novel Food Legislation and its slow execution.     

Sonozonation: Enhancing the antimicrobial efficiency of aqueous ozone washing techniques on cherry tomato

Ultrasound requires high power and longer treatment times to inactivate microorganisms when compared to ultrasound combined with other technologies. Also, the antimicrobial efficiency of aqueous ozone increases with an increase in its concentration and exposure time, but with a detrimental effect on the quality of the treated food. In this study, the effect of aqueous ozone at low concentration, multi-mode frequency irradiation and their combination on microbial safety and nutritional quality of cherry tomato was investigated. Individual washing with aqueous ozone and mono-mode frequency irradiation resulted in <1 log CFU/g reduction in the spoilage microorganisms, while dual-mode frequency irradiation (DMFI) resulted in higher microbial reduction (1.3–2.6 1 log CFU/g). The combined system (20/40 kHz + aqueous ozone) on the other hand, resulted in >3 log CFU/g microbial reduction. The application of DMFI enhanced the antimicrobial efficiency of aqueous ozone without any detrimental effect on the physicochemical properties (except the firmness), bioactive compounds, and antioxidants of the cherry tomato during 21 days refrigerated storage. The result obtained indicates the promising substitute to the single washing technique for microbial safety as well as preserving the nutritional quality and enhancing the shelf life of cherry tomato.     

Overview: Effect of High Pressure on Enzymes Related to Food Quality - Kinetics as a Basis for Process Engineering

In the last decade, high pressure technology received a major interest in food processing/preservation since it offers some advantages especially in retaining food quality attributes ( i.e. colour, flavour and nutritional value). In the framework of defining HACCP guidelines or 'Novel Food' regulation, and also from an engineering point of view, kinetics of pressure process impact on safety and quality aspects of foods are indispensable. In this context, quantitative kinetic studies of the combined pressure and temperature effect on several food related aspects such as food quality related enzymes, pathogenic/spoilage microorganisms, nutritional and sensorial quality characteristics are required. Moreover, from an engineering point of view, such kinetic data are of major importance for evaluation of process uniformity, for process validation and process optimisation.     

Ultrasonics in food processing

In recent years, the physical and chemical effects of ultrasound in liquid and solid media have been extensively used in food processing applications. Harnessing the physical forces generated by ultrasound, in the absence and presence of cavitation, for specific food processing applications such as emulsification, filtration, tenderisation and functionality modification have been highlighted. While some applications, such as filtration and emulsification are "mature" industrial processes, other applications, such as functionality modification, are still in their early stages of development. However, various investigations discussed suggest that ultrasonic processing of food and dairy ingredients is a potential and viable technology that will be used by many food industries in the near future.     

生物传感器的应用

综述了生物传感器的类型、基本原理、目前的研究现状及应用情况。生物传感器是以生物分子作为敏感元件的一类新兴传感器，将化学信号、热信号、光信号转化成电信号或者直接产生电信号予以放大输出，从而得到检测结果。生物传感器广泛应用于食品工业、环境监测、发酵工业、军事领域和临床医学等方面。主要用于一些食品和污染物浓度的测量，微生物呼吸活性的测定，微生物培养方法的选择等，此外，还可以作为水处理设备的终端。可以预料，生物传感器将向着微型化、实用化、多样化和人工智能化的方向发展，并且还将用于对生物功能进行人工模拟，研究人工感官。生物传感器具有快速、准确、方便等优点，具有广阔的应用前景，必将在市场上开辟出一片新的天地。     

A review of recent advances in the decontamination of mycotoxin and inactivation of fungi by ultrasound

Innovative technologies for the pasteurization of food products have increased due to the global demand for higher-quality food products. In this regard, the current article aimed to provide an overview regarding the latest research on US application in the decontamination of fungi in food products and highlight the parameters influencing the effectiveness of this method. Therefore, the related article with inactivation of fungi and mycotoxins by ultrasound among last four years (2018–2021) by using terms such as 'mycotoxin,' 'inactivation,' 'ultrasound,' 'decontamination' among some international databases such as PubMed, Web of Science, Embase and Google Scholar“ was retrieved. Ultrasound (US) is considered a non-thermal decontamination method for food products. In US, the release of energy due to the acoustic phenomenon destroys microorganisms. This technology is advantageous as it is inexpensive, eco-friendly, and does not negatively affect food products' food structure and organoleptic properties. The influence of the US on food structure and organoleptic properties dramatically depends on the intensity and energy density applied In addition, it can preserve higher levels of ascorbic acid, lycopene, and chlorophyll in sonicated food products. The treatment conditions, including frequency, intensity, duration, temperature, and processing pressure, influence the effectiveness of decontamination. However, US displays synergistic or antagonistic effects on bacteria, yeasts, molds, and mycotoxins when combined with other types of decontamination methods such as chemical and thermal approaches. Thus, further research is needed to clarify these effects. Overall, the application of US methods in the food industry for decreasing the microbial content of food products during processing has been applied. However, the use of US with other techniques needs to be studied further.     

近红外光谱技术在微生物检测中的应用进展

近红外光谱作为一种无损检测技术被广泛应用于农业、制药、食品等领域的多组分品质快速监测。微生物的快速准确检测,在临床诊断、制药和食品加工等领域一直是一个难题。微生物菌体细胞壁、细胞膜及细胞内生物大分子和水的近红外光谱具有高度特异性,因此可以使用近红外光谱快速识别和分类不同的微生物。通过对相关文献的归纳整理与分析提炼,对近红外光谱技术在微生物检测中的研究进展做综述。对微生物的基本知识和近红外光谱技术鉴定微生物的基本原理进行了介绍,并重点综述了近红外光谱技术在微生物分类、食源性微生物检测和成像微生物检测等方面的国内外研究进展,最后对近红外光谱技术目前存在的问题和未来的应用前景进行了展望,以期为今后在微生物检测领域更好地利用近红外光谱提供参考。     

Ultrasound and its combined application in the improvement of microbial and physicochemical quality of fruits and vegetables: A review

The eating safety and high quality of fruits and vegetables have always been concerned by consumers, so require a safe, non-toxic, environment-friendly technology for their preservation. The application of ultrasound is a potential technology in the preservation of fruits and vegetables. This paper describes the ultrasound mechanism for inactivating microorganisms, with the cavitation phenomena of ultrasound being considered as a main effect. Effect of ultrasound on microorganisms of fruits and vegetables was discussed. Ultrasound alone and its combined treatments can be an effective method to inactivate the spoilage and pathogenic microorganisms on the surface of fruit and vegetables. Effect of ultrasound on physicochemical quality of fruits and vegetables was reviewed. Ultrasound and its combined treatments reduced mass loss, decreased color change, maintained firmness, enhanced and inhibited enzyme activity as well as preserving nutritional components such as total phenolic, total flavonoids, anthocyanin, and ascorbic acid.     

拉曼光谱技术在病原微生物检测中的应用

病原微生物是指可侵犯人体,引起感染的微生物,临床上由病原微生物感染引发的疾病极为常见。传统的临床病原菌诊断主要依赖于细菌培养,但此方法耗时长,往往需要2～5 d才能得到检测结果,并且存在部分细菌培养困难甚至无法培养的问题。在无法鉴别菌种以及药物敏感性的情况下医生凭借经验使用广谱抗生素,加速了细菌耐药性的产生。因此,病原微生物的高灵敏快速检测方法研究成为重要研究方向。拉曼光谱技术是一种对待测样品进行原位、非侵入性检测的技术,可在单细胞水平上提供微生物细胞中不同生物分子的指纹图谱信息,通过这些信息可以确定微生物的种类、生理特征和突变表型等,实现对微生物样品的快速检测。随着激光光谱学的快速发展以及临床需求的不断增加,促使了以拉曼光谱检测技术为核心的亚技术诞生（如：表面增强拉曼光谱技术、傅里叶变换拉曼光谱技术、激光共振拉曼光谱技术、共聚焦显微拉曼光谱技术、相干反斯托克斯拉曼光谱以及受激拉曼光谱等相关技术）,同时改善了以往拉曼光谱技术信号强度弱的不足,以实现对微生物高精度的快速检测分析。凭借着其具有对样本的状态没有限制以及能够检测物质成分微小变化的优势,近年来对拉曼光谱在病原微生物领域的研究日渐增多。对微生物检测的研究现状进行了调查和分析,围绕着拉曼光谱技术原理对其在微生物检测中的应用进行了具体阐述,其中主要对该技术在病原微生物鉴定以及药敏检测中的研究进展展开讨论,并就其与传统检测技术之间的差别和优势进行分析,展示了拉曼光谱技术作为病原微生物的快速检测新方法的前景。     

Inactivation of Staphylococcus aureus and native microflora in human milk by high pressure processing

The storage of unpreserved food, including breast milk, is associated with the growth of microorganisms, including pathogenic bacteria. It is therefore necessary to use suitable processes to eliminate pathogenic microorganisms and reduce the total microbial count in order to ensure product safety for consumers. In the present study, samples of milk obtained from volunteers donating to the human milk bank were artificially contaminated with Staphylococcus aureus ATCC 6538. This bacteria was the model microorganism of choice, being relatively resistant to high pressure as well as posing the most serious risk to infant health. The results obtained show that high pressure processing can reduce the count of S. aureus by about 5?log units at 4°C and about 8?log units at 50°C, and totally eliminate Enterobacteriaceae after 5?min of treatment, and result in a total microbial count reduction after 10?min treatment at 500?MPa at 20°C and 50°C. This suggests the possibility of this technology being applied to ensure the adequate safety and quality of human breast milk in human milk banks.     

Bioconvection oblique motion of magnetized Oldroyd-B fluid through an elastic surface with suction/injection

In recent research, it is worth mentioning that bioconvection usage has shown significant promise for environmentally friendly, sustainable “green” fuel cell technologies. In this context, the present problem definitely gives a boost to a deeper analysis of the Oldroyd-B fluid model in the presence of gyrotactic microorganisms. This study analyses oblique Oldroyd-B fluid with mixed convection on an elastic surface with interactive properties and gyrotactic microorganisms under the influence of suction/injection with zero heat and mass. The principal physical model is converted in a nonlinear system of ODEs employing proper similarity equations. The impact of all relative physical constrictions on velocity, temperature, concentration, and volume fraction of gyrotactic microorganisms is expressed geometrically. Physical scales like skin friction measurements, heat transfer rate, and mass transfer rate at the surface are calculated numerically.     

Virulence of Listeria monocytogenes before and after high hydrostatic pressure treatment

Abstract

High hydrostatic pressure treatment is regarded as a possible alternative process for food preservation. One of the primary considerations for industrial applications is the ability of this technique to destroy pathogenic microorganisms. The inactivation of microorganism populations after high pressure treatment is well described, but their residual pathogenicity is less documented. This study compared the virulence of Listeria monocytogenes scott A before and after high pressure treatments. The pressurized samples were composed of 1 ml of Listeria monocytogenes culture diluted into 9 ml of buffer. Two buffers are used: phosphate buffer (pH 7) and citrate buffer (pH 5.6).

The virulence of cells is estimated by their association and invasion capacities to Hela cells. These characteristics of pathogenity were compared between untreated and pressurized cells (400 MPa, 10min, in citrate buffer) or (600 MPa, 10min, in phosphate buffer). These results showed that, after treatment in citrate buffer, the treated cells lost their association and invasion capacities. However, in a phosphate buffer, treated cells have lose their invasion properties, but retain their association capacities to Hela cells. These results showed that the inactivation of Listeria monocytogenes population involve a loss of their pathogenic properties. However, the conservation of association capacities of some inactivated cells show that these cells seem to continue to express adhesion molecules and, in certain conditions, can reestablish their multiplication properties.     

Circular polarization in scattered light as a possible biomarker

Biological molecules exhibit homochirality and are optically active. Therefore, it is possible that the scattering of light by biological molecules might result in a macroscopic signature in the form of circular polarization. If this is the case, then circular polarization spectroscopy, which may be utilized in remote sensing, can offer a powerful indicator of the presence of a universal biosignature, namely homochirality. Here, we describe laboratory experiments designed to investigate this idea. We focus on photosynthetic microorganisms, and also show results from macroscopic vegetation and control minerals. In the microorganisms, we find unambiguous circular polarization associated with electronic absorption bands of the photosynthetic apparatus. Macroscopic vegetation yields a stronger and more complex signature while the control minerals produce low-levels of circular polarization unrelated to their spectra. We propose a heuristic explanation of our results, which is that the polarization is produced by circular dichroism in the material after the light has undergone its last scattering event. The results are encouraging for the use of circular polarization spectroscopy in remote sensing of a generic biomarker from space or the ground.